@article{oai:tsukuba.repo.nii.ac.jp:00016003,
 author = {Mikawa, Hiroshi},
 issue = {2},
 journal = {Tsukuba Journal of Mathematics},
 month = {Dec},
 pages = {257--264},
 title = {The differences between consecutive almost-primes},
 volume = {11},
 year = {1987}
}